A self-described hit man who once told police "I kill people for money" pleaded guilty Monday to eight murders, including the contract killing of a Detroit police officer's wife.

Vincent Smothers pleaded guilty to eight counts of second-degree murder and a gun charge in exchange for a minimum sentence of 52 years in prison. With credit for time served since his arrest, he could be freed when he's about 80 years old.

Smothers, 29, shocked police two years ago when he confessed to the eight Detroit slayings during around-the-clock interrogations. He told investigators his hits were all related to the drug trade except for the final one, the killing of Rose Cobb on the day after Christmas in 2007.

"He's just glad there's closure for everybody," defense attorney Gabi Silver told The Associated Press after the hearing in Wayne County Circuit Court, where jury selection was scheduled to begin Monday for the Cobb slaying.

Including Smothers? "Everybody," she replied.

Without the deal, "we'd have to try eight cases," assistant prosecutor Robert Stevens said after the hearing. "It's an equitable resolution with a substantial amount of time."

Cobb, 47, was killed while sitting in her van outside a pharmacy. Police said Smothers, wearing a ski mask, broke a window with a tire iron and shot her in the head.

He told police that Cobb's husband arranged the killing while having an affair. David Cobb was never charged, and he hanged himself in September 2008.

"My stomach was in knots," Smothers told investigators after his April 2008 arrest near his home in Macomb County's Shelby Township. "I felt like she was innocent. ... All the rest were dope dealers."

At another point, he told police: "I don't have a profession. I kill people for money."

Smothers will receive a sentence of 50 years to 100 years in prison for the murders and a two-year punishment for the gun charge when he returns to court on June 24.

Silver had tried to persuade Judge Craig Strong to suppress Smothers' detailed confessions, claiming he incriminated himself only after police agreed not to charge his wife. Police denied any coercion, and the judge refused to throw out the statements.

Smothers told police he was paid $60,000 over a two-year period. In one cold-blooded attack, he admitted killing two men from Chicago, firing through the windshield and the passenger window while they sat in a parked car. He changed weapons without hanging up the phone with the man who hired him.

No one has been prosecuted for hiring Smothers.

During the guilty pleas, the judge mostly asked yes-or-no questions. Smothers answered matter-of-factly and without emotion when pressed to elaborate on some of his killings. He usually didn't talk to the victims.

"I was walking down the street and they were walking out of the house. I walked up and shot them," Smothers told Strong, describing an incident.

Outside court, Rose Cobb's sister, Sheryl Gary, said she was satisfied with the plea deal.

"Bottom line, it's over," she said. "It's plain, simple and we don't have to be taken through a drawn-out trial."